Re: DRC and your room
Yes, I understand the limitations of electronic and how it can't change or influence certain things. In simplistic terms what it will do is smarten up the bass and create a more coherent sound through smoothing phase and amplitude errors in and around the listening position.
In the last few days I've done a good amount of research into the problems associated with small rooms. The general consensus is they benefit from large amounts of absorption simply because the decay time is too short to provide any useful ambience. Our brains can distinguish two sources of sound, say direct and reflected in this case, as long as the delay is approximately over 20ms. Anything less and its masks details and imaging. Anything over this and we understand it as two separate sources and can start to interpret as ambience, echo etc.
Lots of absorption mixed with a small amount of live surfaces is a good thing in a small room.
I'm no expert however and read and understood this in an article from Ethan Winer. Its also explored in a heavy going fashion in Everest' "Master Handbook of Acoustics".
Narrow directivity might be a boon at this point but I don't plan on trying any such designs in the near future so it'll probably be a way off before I could say conclusively.
Couldn't I just send you the room and keep the speakers?
badman said:
Yes, I understand the limitations of electronic and how it can't change or influence certain things. In simplistic terms what it will do is smarten up the bass and create a more coherent sound through smoothing phase and amplitude errors in and around the listening position.
In the last few days I've done a good amount of research into the problems associated with small rooms. The general consensus is they benefit from large amounts of absorption simply because the decay time is too short to provide any useful ambience. Our brains can distinguish two sources of sound, say direct and reflected in this case, as long as the delay is approximately over 20ms. Anything less and its masks details and imaging. Anything over this and we understand it as two separate sources and can start to interpret as ambience, echo etc.
Lots of absorption mixed with a small amount of live surfaces is a good thing in a small room.
I'm no expert however and read and understood this in an article from Ethan Winer. Its also explored in a heavy going fashion in Everest' "Master Handbook of Acoustics".
Narrow directivity might be a boon at this point but I don't plan on trying any such designs in the near future so it'll probably be a way off before I could say conclusively.
Couldn't I just send you the room and keep the speakers?
Have you tried contacting Bryan at www.gikacoustics.com about your room Shin?
He is always willing to help people out.
He is always willing to help people out.
Re: Re: Shame to cripple such speakers
Hi Shin,
In this case , you typically have a sofa directly on the rear wall.
Your ears are about 40-50 cm from the wall. Very bad but I have
experimentate this scenario ( a friend of mine) with a big absorber
fluffy dacron/ felt wool 1,5x1x0,35 meters and it works good if you
kill the VER from the front wall (and the side ER). The only cons is the big boost plus a null in the LF but you have DRC , no?
Imo it is interesting/praticable if you remove that reflective stuff
between the two wonderful speakers
just my opinion,
Paolo
ShinOBIWAN said:
Hi Shin,
In this case , you typically have a sofa directly on the rear wall.
Your ears are about 40-50 cm from the wall. Very bad but I have
experimentate this scenario ( a friend of mine) with a big absorber
fluffy dacron/ felt wool 1,5x1x0,35 meters and it works good if you
kill the VER from the front wall (and the side ER). The only cons is the big boost plus a null in the LF but you have DRC , no?
Imo it is interesting/praticable if you remove that reflective stuff
between the two wonderful speakers
just my opinion,
Paolo
Re: Re: Re: Shame to cripple such speakers
Hi Paolo
Unfortunately I'm not even 40-50cm away from the wall with the speakers firing across the width of the room. Its more like 10-15cm once you've got the 60 degree equilateral triangle setup done.
The room really isn't suited to audio unfortunately but I'll have to make do for now.
inertial said:
Hi Shin,
In this case , you typically have a sofa directly on the rear wall.
Your ears are about 40-50 cm from the wall. Very bad but I have
experimentate this scenario ( a friend of mine) with a big absorber
fluffy dacron/ felt wool 1,5x1x0,35 meters and it works good if you
kill the VER from the front wall (and the side ER). The only cons is the big boost plus a null in the LF but you have DRC , no?
Imo it is interesting/praticable if you remove that reflective stuff
between the two wonderful speakers
just my opinion,
Paolo
Hi Paolo
Unfortunately I'm not even 40-50cm away from the wall with the speakers firing across the width of the room. Its more like 10-15cm once you've got the 60 degree equilateral triangle setup done.
The room really isn't suited to audio unfortunately but I'll have to make do for now.
This is pretty much finished now and gives a very good idea of the final look and layout.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Re: Re: Re: Re: Shame to cripple such speakers
Hi Shin,
just to be precise, It seems to me very strange about 10-15cm only.
This can happen if your head touch the rear wall only
Normally the thick of the sofa is consistent, imagine to extend the back
like a sort of giant headrest.
And I think also equilateral triangle is not always the only choice.
Just my opinion .
cheers,
Paolo
ShinOBIWAN said:
Hi Shin,
just to be precise, It seems to me very strange about 10-15cm only.
This can happen if your head touch the rear wall only
Normally the thick of the sofa is consistent, imagine to extend the back
like a sort of giant headrest.
And I think also equilateral triangle is not always the only choice.
Just my opinion .
cheers,
Paolo
Based on a suggestion I've now updated to include 4" thick rockwool on all surfaces within the alcoves where the speakers sit. Baffles protrude out from the cabinet by just over a foot. This should help with bass related issues.
I round up a few mates this evening and between us we had finely tuned production line going. Amazingly within 3 hours we'd gone from nothing to virtually all the 1st stage of the framework complete.
The photo's aren't great quality but here's what we got done.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I round up a few mates this evening and between us we had finely tuned production line going. Amazingly within 3 hours we'd gone from nothing to virtually all the 1st stage of the framework complete.
The photo's aren't great quality but here's what we got done.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hi ShinOBIWAN,
did you do any measurements with provisional mounted absorbers? If not I'll expect the sound becoming dull because the absorber as shown in your pictures is not broadband enough. The porous material is not thick enough and the air gap behind the absorbers is not big enough to absorb low and mid frequencies.
Best, Markus
did you do any measurements with provisional mounted absorbers? If not I'll expect the sound becoming dull because the absorber as shown in your pictures is not broadband enough. The porous material is not thick enough and the air gap behind the absorbers is not big enough to absorb low and mid frequencies.
Best, Markus
markus76 said:
Hey Markus
Ignore the framework shown in the photo's, its not indicative of the final depth since there's some additional framework needed that will build the final depth to 80mm. Its only around 45mm at the moment.
I'll be using 75mm RW5 mounted directly to the wall. Its effective from 200hz up with somewhat useful to 125hz. This covers the highs, mids and mid bass. So I'd consider that reasonably broadband.
Here's the NRC data for Rockwool. A rating of 1.0 is total absorption.
An externally hosted image should be here but it was not working when we last tested it.
Taming bass below 150hz requires large traps, much larger than the room can support. DRC will have to do here. I don't anticipate any major tonal imbalances or at least nothing that can't be worked out with a target curve. I won't know for sure until I try it though.
I do plan to dry run once the room is moved on a little. I realise I can tweak the absorption on the upper end with thin materials such as paper, card, perforated 3mm chipboard etc. for progressively more reflectivity at lower and lower frequencies points.
You can get much better low frequency absorption when optimizing the thickness of the porous material and the air gap (air gap = thickness of absorber is a good rule of thumb). You can somewhat calculate the effectivity with this Excel sheet:
http://www.whealy.com/acoustics/Porous.html
But in nearly every room absorption of the low frequencies (especially behind the speakers to make the speakers polar response more uniform) is much more important than minimizing first reflections. To further enhance effectivity for low frequencies, the absorbers should be mounted in the corners of a room.
Best, Markus
http://www.whealy.com/acoustics/Porous.html
But in nearly every room absorption of the low frequencies (especially behind the speakers to make the speakers polar response more uniform) is much more important than minimizing first reflections. To further enhance effectivity for low frequencies, the absorbers should be mounted in the corners of a room.
Best, Markus
I agree if the speakers are less than 30 cm (= 1 ms delay between direct and reflected sound) away from the side walls. Otherwise lateral reflections can contribute to speech intelligibility.
Furthermore ShinOBIWAN has more absorption on the left wall than on the right wall. I'm not sure if this doesn't lead to wrong spatial cues and therefore has a negative effect on imaging.
Best, Markus
Furthermore ShinOBIWAN has more absorption on the left wall than on the right wall. I'm not sure if this doesn't lead to wrong spatial cues and therefore has a negative effect on imaging.
Best, Markus
markus76 said:
Its possible to solve that by attaching reflective material in front of the rockwool and behind the fabric at various points through the room. Depending on how thick that material is and whether its perforated or not then you can tune the rough frequency point and up where absorption no longer occurs. Below that point you still retain absorption since the wavelength ignore the reflective material.
Any further tonal imbalances due to non symmetry can be tweaked out through DRC to ensure consistent frequency performance between the left and right loudspeaker at the listening position.
This will be looked at with the dry run of the room. If I find the image is being pulled to right because of the window then I'll make the left wall slightly more reflective at mid to high frequencies.
markus76 said:
Did you miss the part where I mentioned tweaking reflectivity? I'm hardly relying completely on DRC to solve something it isn't entirely capable of doing by itself.
I've been using DRC and digital crossovers in some form or another for over 3 years now. I've heard them work and work well. But some luck is always nice
As to your resistance towards DRC; you'd never accept an amp with a +/-15dB frequency response with all manner of phase shifts. How can making that better be something not to be enthusiastic about? I ask because DRC is proven to work to reduce these up to around 30% in best case scenarios. I think its traditional thinking that's holding you back or you've yet to have exposure to effective DRC.
I think if you ignore this and not consider DRC then your accepting another the greater burden of a compromise IMO.
First things first. If stuck in a really bad room - speaker mating, its better to distort the input signal for rectifying gross amplitude errors. It adds artificiality arguably but what to do better if between a rock and a hard place?
Best is to go Geddes from planning phase in such matters.
Best is to go Geddes from planning phase in such matters.
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